a particle with mass $4\mathrm{.}0$ x $10^-20$ kg is oscillating with simple harmonic motion with a period of $1\mathrm{.}2$ x $10^-5$ s and a maximum speed of $2\mathrm{.}8$ x $10^3$ m$/$s$.$ Calculate $($a$)$ the angular frequency and $($b$)$ the maximum displacement of the particle.